1. Field of the Invention
The invention relates generally to crop harvesting combines and more particularly to a system for controlling the crop threshing mechanism to minimize crop damage within the threshing mechanism.
2. Prior Art
Applicants are unaware of any prior art which controls the speed of a crop threshing and separating mechanism in response to sensing a ratio of damaged to undamaged grain as processed in the threshing and separating mechanism. It is old to effect the control of the speed of a crop harvesting cylinder as in U.S. Pat. Nos. 3,609,947; 3,910,286; 3,897,677; and 3,606,742. In the above '286 patent, cylinder speed is sensed and a "control means 29" (shown as a square in FIG. 2) may stop the cylinder, lift the table, or stop the machine. In above patent '677 the angle of the feeder is sensed as indicative of possible jamming of the threshing cylinder and a warning is given or a "control" effected. As in above patent '286 the "control means 29" is not further defined or described. In any case, neither patent is concerned with crop damage responsive controls. Above patent '947 likewise has no relation to crop damage and controls responsive thereto.
The standard practice of determining grain damage is by visual inspection or taking a sample to a facility wherein dockage checks are made to determine the amount of grain damage. The combine operator then adjusts the machine with the hope that the new operating parameters will minimize crop damage while maintaining reasonable harvesting rates. In making such adjustments the operator would be concerned with maintaining relatively high threshing rotor speeds since less power is required to thresh and move crop through a rotor at higher rotor speeds. Variations in crop type, toughness, and moisture content are also variables to be taken into account. At best, under current practice the operator is using an educated guess as to optimum rotor speeds for minimal crop damage.